How to open an EML file

A .eml file is just an email saved to disk. Here is how to read one when nothing on your computer will.

Open your EML file now

Drag the file into the viewer and read the sender, the message and the attachment list straight away. The file is parsed in your browser and never uploaded.

Open the EML viewer

Or read the guide below first.

Why your computer will not open it

An .eml file is a single email saved to disk: headers, message body and attachments, all encoded as text in the format defined by RFC 5322. Nothing about it is proprietary, and nothing about it is locked. The reason a double-click does nothing is simpler than it looks: no program on your machine has registered itself as the owner of that extension.

That is common on a work laptop with webmail instead of a desktop client, on a Mac where Mail was never set up, and on a phone, where files that arrive as attachments have nowhere obvious to go.

Opening it in the browser

Save the .eml file somewhere you can find it — the desktop is fine.
Open the viewer and drag the file onto the drop area, or click to pick it.
The sender, recipients, subject, date, message body and attachment list appear straight away.

What stays on your machine

The parsing runs in your browser. There is no upload step, no server copy and no account. For an email — which routinely carries contracts, invoices and other people's personal data — that distinction matters more than convenience.

Opening it with software you already have

Outlook (Windows) — double-clicking usually works if Outlook is installed, because it claims the .eml extension during setup.
Apple Mail (macOS) — double-click the file and it opens as a message window.
Mozilla Thunderbird — File → Open → Saved Message, then pick the file.
Any text editor — it will show the raw source. Readable in principle, unpleasant in practice: the body is often Base64 or quoted-printable encoded, so you will see blocks of characters rather than the message.

Webmail is the exception. Gmail and Outlook on the web cannot open a local .eml file: there is no import for a single message, which is exactly why people end up looking for another way.

Reading more than the message

Every email carries a header block recording the servers it passed through and the results of the authentication checks run on the way. The viewer shows them, including the SPF, DKIM and DMARC outcomes recorded by the receiving server.

That is the part worth looking at when a message seems suspicious. A display name is trivial to fake; an authentication result recorded by the server that accepted the message is not.

Frequently asked questions

Can I open an EML file without Outlook?

Yes. An EML file is a plain-text file that follows the RFC 5322 standard, so it does not need Outlook or any other mail client. Drop it into the viewer above and the message is parsed in your browser.

Is it safe to open a confidential email here?

Nothing is uploaded. The file is read by JavaScript running in your own browser, and the content never leaves your device. You can confirm this yourself: open your browser's network panel, drop a file in, and you will see no request carrying the message.

Why does my computer not know what to do with a .eml file?

Because no application has claimed that extension. On Windows this happens when neither Outlook nor another desktop mail client is installed; on macOS it happens when Mail has been removed or the file came from a different system. The file itself is perfectly readable — it is the association that is missing.

Can I see the attachments?

The viewer lists every attachment with its name, type and size for free. Downloading an attachment or exporting the message as PDF requires a one-off unlock or a Pro plan.

Does it work on a phone?

Yes. It runs in mobile Safari and Chrome, which is useful because phones are where EML attachments are hardest to open.